1 files changed, 187 insertions, 0 deletions
diff --git a/zerotierone/node/SelfAwareness.cpp b/zerotierone/node/SelfAwareness.cpp
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+++ b/zerotierone/node/SelfAwareness.cpp
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+/*
+ * ZeroTier One - Network Virtualization Everywhere
+ * Copyright (C) 2011-2016  ZeroTier, Inc.  https://www.zerotier.com/
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <set>
+#include <vector>
+
+#include "Constants.hpp"
+#include "SelfAwareness.hpp"
+#include "RuntimeEnvironment.hpp"
+#include "Node.hpp"
+#include "Topology.hpp"
+#include "Packet.hpp"
+#include "Peer.hpp"
+#include "Switch.hpp"
+
+// Entry timeout -- make it fairly long since this is just to prevent stale buildup
+#define ZT_SELFAWARENESS_ENTRY_TIMEOUT 3600000
+
+namespace ZeroTier {
+
+class _ResetWithinScope
+{
+public:
+	_ResetWithinScope(uint64_t now,InetAddress::IpScope scope) :
+		_now(now),
+		_scope(scope) {}
+
+	inline void operator()(Topology &t,const SharedPtr<Peer> &p)
+	{
+		if (p->resetWithinScope(_scope,_now))
+			peersReset.push_back(p);
+	}
+
+	std::vector< SharedPtr<Peer> > peersReset;
+
+private:
+	uint64_t _now;
+	InetAddress::IpScope _scope;
+};
+
+SelfAwareness::SelfAwareness(const RuntimeEnvironment *renv) :
+	RR(renv),
+	_phy(32)
+{
+}
+
+SelfAwareness::~SelfAwareness()
+{
+}
+
+void SelfAwareness::iam(const Address &reporter,const InetAddress &receivedOnLocalAddress,const InetAddress &reporterPhysicalAddress,const InetAddress &myPhysicalAddress,bool trusted,uint64_t now)
+{
+	const InetAddress::IpScope scope = myPhysicalAddress.ipScope();
+
+	if ((scope != reporterPhysicalAddress.ipScope())||(scope == InetAddress::IP_SCOPE_NONE)||(scope == InetAddress::IP_SCOPE_LOOPBACK)||(scope == InetAddress::IP_SCOPE_MULTICAST))
+		return;
+
+	Mutex::Lock _l(_phy_m);
+	PhySurfaceEntry &entry = _phy[PhySurfaceKey(reporter,receivedOnLocalAddress,reporterPhysicalAddress,scope)];
+
+	if ( (trusted) && ((now - entry.ts) < ZT_SELFAWARENESS_ENTRY_TIMEOUT) && (!entry.mySurface.ipsEqual(myPhysicalAddress)) ) {
+		// Changes to external surface reported by trusted peers causes path reset in this scope
+		entry.mySurface = myPhysicalAddress;
+		entry.ts = now;
+		TRACE("physical address %s for scope %u as seen from %s(%s) differs from %s, resetting paths in scope",myPhysicalAddress.toString().c_str(),(unsigned int)scope,reporter.toString().c_str(),reporterPhysicalAddress.toString().c_str(),entry.mySurface.toString().c_str());
+
+		// Erase all entries in this scope that were not reported from this remote address to prevent 'thrashing'
+		// due to multiple reports of endpoint change.
+		// Don't use 'entry' after this since hash table gets modified.
+		{
+			Hashtable< PhySurfaceKey,PhySurfaceEntry >::Iterator i(_phy);
+			PhySurfaceKey *k = (PhySurfaceKey *)0;
+			PhySurfaceEntry *e = (PhySurfaceEntry *)0;
+			while (i.next(k,e)) {
+				if ((k->reporterPhysicalAddress != reporterPhysicalAddress)&&(k->scope == scope))
+					_phy.erase(*k);
+			}
+		}
+
+		// Reset all paths within this scope
+		_ResetWithinScope rset(now,(InetAddress::IpScope)scope);
+		RR->topology->eachPeer<_ResetWithinScope &>(rset);
+
+		// Send a NOP to all peers for whom we forgot a path. This will cause direct
+		// links to be re-established if possible, possibly using a root server or some
+		// other relay.
+		for(std::vector< SharedPtr<Peer> >::const_iterator p(rset.peersReset.begin());p!=rset.peersReset.end();++p) {
+			if ((*p)->activelyTransferringFrames(now)) {
+				Packet outp((*p)->address(),RR->identity.address(),Packet::VERB_NOP);
+				RR->sw->send(outp,true,0);
+			}
+		}
+	} else {
+		// Otherwise just update DB to use to determine external surface info
+		entry.mySurface = myPhysicalAddress;
+		entry.ts = now;
+	}
+}
+
+void SelfAwareness::clean(uint64_t now)
+{
+	Mutex::Lock _l(_phy_m);
+	Hashtable< PhySurfaceKey,PhySurfaceEntry >::Iterator i(_phy);
+	PhySurfaceKey *k = (PhySurfaceKey *)0;
+	PhySurfaceEntry *e = (PhySurfaceEntry *)0;
+	while (i.next(k,e)) {
+		if ((now - e->ts) >= ZT_SELFAWARENESS_ENTRY_TIMEOUT)
+			_phy.erase(*k);
+	}
+}
+
+std::vector<InetAddress> SelfAwareness::getSymmetricNatPredictions()
+{
+	/* This is based on ideas and strategies found here:
+	 * https://tools.ietf.org/html/draft-takeda-symmetric-nat-traversal-00
+	 *
+	 * In short: a great many symmetric NATs allocate ports sequentially.
+	 * This is common on enterprise and carrier grade NATs as well as consumer
+	 * devices. This code generates a list of "you might try this" addresses by
+	 * extrapolating likely port assignments from currently known external
+	 * global IPv4 surfaces. These can then be included in a PUSH_DIRECT_PATHS
+	 * message to another peer, causing it to possibly try these addresses and
+	 * bust our local symmetric NAT. It works often enough to be worth the
+	 * extra bit of code and does no harm in cases where it fails. */
+
+	// Gather unique surfaces indexed by local received-on address and flag
+	// us as behind a symmetric NAT if there is more than one.
+	std::map< InetAddress,std::set<InetAddress> > surfaces;
+	bool symmetric = false;
+	{
+		Mutex::Lock _l(_phy_m);
+		Hashtable< PhySurfaceKey,PhySurfaceEntry >::Iterator i(_phy);
+		PhySurfaceKey *k = (PhySurfaceKey *)0;
+		PhySurfaceEntry *e = (PhySurfaceEntry *)0;
+		while (i.next(k,e)) {
+			if ((e->mySurface.ss_family == AF_INET)&&(e->mySurface.ipScope() == InetAddress::IP_SCOPE_GLOBAL)) {
+				std::set<InetAddress> &s = surfaces[k->receivedOnLocalAddress];
+				s.insert(e->mySurface);
+				symmetric = symmetric||(s.size() > 1);
+			}
+		}
+	}
+
+	// If we appear to be symmetrically NATed, generate and return extrapolations
+	// of those surfaces. Since PUSH_DIRECT_PATHS is sent multiple times, we
+	// probabilistically generate extrapolations of anywhere from +1 to +5 to
+	// increase the odds that it will work "eventually".
+	if (symmetric) {
+		std::vector<InetAddress> r;
+		for(std::map< InetAddress,std::set<InetAddress> >::iterator si(surfaces.begin());si!=surfaces.end();++si) {
+			for(std::set<InetAddress>::iterator i(si->second.begin());i!=si->second.end();++i) {
+				InetAddress ipp(*i);
+				unsigned int p = ipp.port() + 1 + ((unsigned int)RR->node->prng() & 3);
+				if (p >= 65535)
+					p -= 64510; // NATs seldom use ports <=1024 so wrap to 1025
+				ipp.setPort(p);
+				if ((si->second.count(ipp) == 0)&&(std::find(r.begin(),r.end(),ipp) == r.end())) {
+					r.push_back(ipp);
+				}
+			}
+		}
+		return r;
+	}
+
+	return std::vector<InetAddress>();
+}
+
+} // namespace ZeroTier